What is it ???

[sparks_vfr]

I have attached a circuit diagram that I am going to attempt to re-create...

I do not want to control anything so will not be using U3

My problem is, the symbol for C3 is not something I have seen before (I have not seen that many circuit diagrams)

Is it a polarised Cap ? That I believe is supposed to be shown as **broken link removed**

I would also like to monitor 16 analog devices, would I be able to use an AD7490 as a direct replacement for the ADC0808 ??**broken link removed**

Sparks

 

[Norlin]

just a non-polarized capacitor, this table might be useful:
**broken link removed**

 

[ericgibbs]

I have attached a circuit diagram that I am going to attempt to re-create...

I
I would also like to monitor 16 analog devices, would I be able to use an AD7490 as a direct replacement for the ADC0808 ??**broken link removed**

Sparks

hi,
Its the symbol for a polarised capacitor.
The flat line represents the postive terminal and the curved line the negative, most likely an electrolytic or tantalum cap.

The AD7490 uses a totally different communication method, between the PIC and ADC0808.
It would mean a revised circuit and a new program.

Does this help.?

 

[sparks_vfr]

hi,
Its the symbol for a polarised capacitor.
The flat line represents the postive terminal and the curved line the negative, most likely an electrolytic or tantalum cap.

The AD7490 uses a totally different communication method, between the PIC and ADC0808.
It would mean a revised circuit and a new program.

Does this help.?

Thanks for the cap info, I sort of guess that might be the case but thought I'd ask just in case..

Bummer, is the only diagram I could find that keeps things nice and simple and does almost exactly what I want (Apart from me wanting to read 16 analog sensors)..

Any ideas on how to move forward, a multiplexer was suggested with 2 0808's, but I have no idea what to search for on RS and how to implement it with the 0808..

Sparks

 

[ericgibbs]

hi Sparks,
Are you able to write the program for a 89c51 controller..?
or say a PIC 16Fxxx controller.?

I am assuming that you want to monitor, 16, LM35 temperature sensors?
What do you plan to do with the analog signals once you have captured them.?

Like to help, but we really need more details of the project.

 

[sparks_vfr]

hi Sparks,
Are you able to write the program for a 89c51 controller..?
or say a PIC 16Fxxx controller.?

have done some programming in the past, C, perl, python.. Did some asm once on my Amiga when they first came out !!! Am, sure I could pick it up pretty quickly, using ref mans and such

I am assuming that you want to monitor, 16, LM35 temperature sensors?
What do you plan to do with the analog signals once you have captured them.?

Like to help, but we really need more details of the project.

It's for monitoring temp and pressure sensors that are already on an engine, the data I want to stream to a serial port. Linux live cd type system with GUI monitor console etc...

Once I can start sampling data I can get the fine details hashed out and looking slick.. That side will only take a few days.. Is the hardware side I am having the problems, i have fiddled and dabbled in electronics before, but am finding I'm out of my depth, but am willing to learn..

Sparks

 

[blueroomelectronics]

Why don't you contact the designer Abbas Raza?
The LM35 also has a maximum temperature range 150c, an engine would probably be much hotter.
**broken link removed**

 

[sparks_vfr]

Why don't you contact the designer Abbas Raza?
The LM35 also has a maximum temperature range 150c, an engine would probably be much hotter.
**broken link removed**

I'm not planning on using the LM35's they were just what he had put on the diagram, as I mentioned I am hoping to be able to use the sensors already in place..

Sparks

 

[blueroomelectronics]

What sensors are you using?

 

[sparks_vfr]

What sensors are you using?

The sensors are earth return (two wires, + and - ) all the sensors I have tested/checked so far just use resistance.

So based on that my plan is to put a measured voltage through (5v) and measure it, the output then sent via serial to a PC which can then with simple algorithms give a "readable" output (is actually going to be gauges). Goes without saying there will be some basic calibration involved, this will be sorted with a config file for the software on the PC.

My idea is to have the PIC do as little as possible (As I know more about PC/Linux programming) then I do about the PIC side of things, my asm/C isn't upto the task at the moment.. Maybe time to start ?

Sparks


P.S. I have contacted Abbas Raza, the circuit designer for some input as well, and he has sent me a very nice email saying he will have a look as well

 

[blueroomelectronics]

Are you using a thermocouple? You'll need to amplify the signal if so.
Do you have a part number for them?

 

[sparks_vfr]

Are you using a thermocouple? You'll need to amplify the signal if so.
Do you have a part number for them?

I have no idea !!!

Part numbers ! They are not available it is a Russian Shvetsov Ash21 engine, and is about a 1000 years old ! (Ok, maybe a bit of exaggeration there)..

Slight change to angle here, maybe it can be simplified ?

Throw 5v down the line, measure the voltage that comes back, send data to serial port.. I guess thats what the ADC does ? (Thinking out-loud!)

I did not honestly think it would be this complicated to need part numbers, as has already been said "the devil is in the details".. On paper it does sound simple and using a multimeter I can see the resistance change, so in my simple world I though all I needed to do was measure the resistance and squirt it to the PC for that to process the value sent and display accordingly..

However, this has really got the "old grey matter" working on trying to follow what and why these questions are being asked so I can try and solve the problem, or at least understand any possible solutions put forward..

Sparks

 

[kchriste]

Since you are a PC guy, why don't you skip the PIC or microcontroller and do it via the parallel port:
https://linuxgazette.net/118/chong.html

 

[blueroomelectronics]

You've got to figure out what those sensors are, they are probably millivolt thermocouples and you'll need some signal conditioning before the A/D to get any useful readings.

What is the resistance change, have you made a chart? Min / Max?

 

[sparks_vfr]

You've got to figure out what those sensors are, they are probably millivolt thermocouples and you'll need some signal conditioning before the A/D to get any useful readings.

What is the resistance change, have you made a chart? Min / Max?

Nope but I will make a chart today


Sparks

 

[sparks_vfr]

Since you are a PC guy, why don't you skip the PIC or microcontroller and do it via the parallel port:
https://linuxgazette.net/118/chong.html

Already in my bookmarks thanks

Trouble is thats only 8 inputs, I want 16 ..

Sparks

 

[ericgibbs]

Already in my bookmarks thanks

Trouble is thats only 8 inputs, I want 16 ..

Sparks

hi,
Getting 16 inputs is not a problem with a PC's parallel port.

Use two ADC 0808 and two parallel output pins to select ADC #1 or #2, using the OE pins on the ADC0808

Do you follow that.?

 

[sparks_vfr]

hi,
Getting 16 inputs is not a problem with a PC's parallel port.

Use two ADC 0808 and two parallel output pins to select ADC #1 or #2, using the OE pins on the ADC0808

Do you follow that.?

That is excellent news, I think I follow.. I'll see if I can use my mastery of MSPaint and fuddle a diagram together

Many Thanks..

Sparks